Controller for automobile

ABSTRACT

A nonvolatile memory built in a vehicle control computer and storing control software and an auxiliary storage for setting an unerasable region to the nonvolatile memory and updating the control software in an erasable region to new control software are used.

TECHNICAL FIELD

[0001] The present invention relates to a vehicle controller capable ofchanging control software to a control algorithm newly developed toimprove the performance early and by a relatively inexpensive apparatusin a market after selling a vehicle.

BACKGROUND ART

[0002] An electric-power-steering controller is described below as oneof the conventional vehicle controllers. FIG. 3 is a circuit diagram ofthe conventional power-steering controller disclosed in Japanese PatentApplication No. 5-64268 in which a part of the controller is shown by ablock diagram. In FIG. 3, a motor 40 for outputting an auxiliary torqueto a vehicle steering wheel (not illustrated) is driven by a motorcurrent IM supplied from a battery 41. The ripple component of the motorcurrent IM is absorbed by a capacitor 42 having a large capacity (1,000μF to 3,600 μF) and detected by a shunt resistor 43. Moreover,directions and values of the motor current IM are switched in accordancewith the operation of a bridge circuit 44 having a plurality ofsemiconductor switching devices (e.g. FETs) Q1 to Q4 in accordance withthe magnitude and direction of the auxiliary torque.

[0003] One end of the capacitor 42 is connected to the ground by aconductive wire L1. The semiconductor switching devices Q1 to Q4 arebridge-connected by wiring patterns P1 and P2 to constitute a bridgecircuit 44. Moreover, the wiring patterns P1 and P2 connect the bridgecircuit 44 to the shunt resistor 43. The output terminal of the bridgecircuit 44 is constituted with a wiring pattern P3.

[0004] The motor 40 and battery 41 are connected to the bridge circuit44 through the wiring pattern P3 by a connector 45 having a plurality oflead terminals. The motor 40 and battery 41 are connected to theconnector 45 by an external wiring L2. The motor current IM is suppliedor cut off by a normally-open relay 46 according to necessity. The relay46, capacitor 42, and shunt resistor 43 are connected each other by awiring pattern P4. The connector 45 is connected to the ground by awiring pattern P5. The wiring pattern P3 serving as the output terminalof the bridge circuit 44 is connected to the connector 45.

[0005] The motor 40 is driven by a driving circuit 47 through the bridgecircuit 44. Moreover, the driving circuit 47 drives the relay 46. Thedriving circuit 47 is connected to the exciting coil of the relay 46 bya conductive wire L3. Moreover, the driving circuit 47 is connected tothe bridge circuit 44 by a conductive wire L4. The motor current IM isdetected by a motor current detection means 48 in accordance with thevoltage appearing at the both ends of the shunt resistor 43. The drivingcircuit 47 and motor current detection means 48 constitute theperipheral circuit element of a microcomputer 55 to be mentioned later.

[0006] The steering torque T of a steering wheel is detected by a torquesensor 50 and the speed V of a vehicle is detected by a speed sensor 51.The microcomputer 55 (ECU) computes an auxiliary torque in accordancewith the steering torque T and vehicle speed V, generates a drivingsignal corresponding to the auxiliary torque by returning the motorcurrent IM, and outputs a rotational direction command D₀ and a currentcontrolled variable I₀ for controlling the bridge circuit 44 to thedriving circuit 47 as driving signals.

[0007] The microcomputer 55 is provided with motor current decisionmeans 56 for generating the rotational direction command D₀ for themotor 40 and a motor current command Im corresponding to an auxiliarytorque, subtraction means 57 for computing a current deviation ΔIbetween the motor current command Im and the motor current IM, and PIDoperation means 58 for computing correction values of P (proportion)term, I (integration) term, and D (differentiation) term in accordancewith the current deviation ΔI and generating the current controlledvariable I₀ corresponding to a PWM duty ratio.

[0008] Moreover, though not illustrated, the microcomputer 55 includes apublicly-known self-diagnostic function in addition to an AD converterand a PWM timer circuit, always self-diagnoses whether a system normallyoperates, and cuts off the motor current IM by releasing the relay 46through the driving circuit 47 when a trouble occurs. The microcomputer55 is connected to the driving circuit 47 through a conductive wire L5.

[0009] Then, operations of a conventional electric-power-steeringcontroller are described below by referring to FIG. 3. The microcomputer55 captures the steering torque T and vehicle speed V from the torquesensor 50 and speed sensor 51, feedback-inputs the motor current IM fromthe shunt resistor 43, and generates the rotational direction command D₀of a power steering and the current controlled variable I₀ correspondingto an auxiliary torque to output them to the driving circuit 47 throughthe conductive wire L5.

[0010] The driving circuit 47 closes the normally-open relay 46 inaccordance with a command through the conductive wire L3 under anormally driving state but it generates a PWM driving signal when therotational direction command D₀ and current controlled variable I₀ areinput and applies the signal to the semiconductor switching devices Q1to Q4 of the bridge circuit 44 through the conductive wire L4.

[0011] According to the above circuit structure, the motor current IM issupplied from the battery 41 to the motor 40 through the external wiringL2, connector 45, relay 46, wiring pattern P4, shunt resistor 43, wiringpattern P1, bridge circuit 44, wiring pattern P3, connector 45, andexternal wiring L2. The motor 40 is driven by the motor current IM tooutput a required mount of auxiliary torque in a required direction.

[0012] In this case, the motor current IM is detected through the shuntresistor 43 and motor current detection means 48 and returned to thesubtraction means 57 in the microcomputer 55 and thereby, controlled soas to coincide with the motor current command Im. Moreover, though themotor current IM includes ripple components because of the switchingoperation of the bridge circuit 44 under PWM driving, it is smoothed andcontrolled by the large-capacity capacitor 42.

[0013] A vehicle controller including this type ofelectric-power-steering controller conventionally uses a microcomputerhaving a built-in mask ROM storing control software such as control dataand control programs.

[0014] However, because it is necessary to secure a predetermined maskROM fabrication period under short-time system development, it is nottemporally permitted to re-fabricate a mask ROM due to re-modificationof software specification and it is necessary to early fix the softwarespecification. Therefore, this causes the loads of development engineersto increase.

[0015] Moreover, also when changing control software for anewly-developed control algorithm in order to improve the performance ina market, it is necessary to secure a predetermined mask ROM fabricationperiod. However, it is impossible to re-fabricate a mask ROM because ofchanging the control software for the newly-developed control algorithmand to early change the control software in accordance with thenewly-developed control algorithm. Furthermore, to reload the controlsoftware in a market, it is necessary to prepare an inexpensiveauxiliary storage.

[0016] General control software is constituted with the part of discretecorresponding data between an input/output unit connected to acontroller and the controller, the part of intrinsic data (e.g.torque-sensor neutral point learning data after final combination of thetorque sensor 50 serving as an input/output unit with the controller ofa vehicle or trouble history data in the controller mounted on a vehiclein a market after selling the vehicle), and the part of controlalgorithm.

[0017] Thus, the stored intrinsic data content of the intrinsic datastorage block (region) in the control software of a storage to bementioned later corresponds to each input/output unit and the controllerone to one. Therefore, to reload the control software in a market, it isnecessary to change the intrinsic data storage block (region) to anunerasable block (region).

[0018] The present invention is made to solve the above problem and itsobject is to provide a vehicle controller making it possible torelatively inexpensively, easily, early change control software in amarket after selling the vehicle correspondingly to performanceimprovement.

DISCLOSURE OF THE INVENTION

[0019] 1. An occasionally-erasable nonvolatile memory built in a vehiclecontrol computer and storing control processing information andauxiliary storage means for setting an unerasable region to theoccasionally-erasable nonvolatile memory and updating the controlprocessing information in an erasable region to new control processinginformation are used.

[0020] 2. The auxiliary storage means is constituted by adding aninformation writing function to the occasionally-erasable nonvolatilememory of a troubleshooting unit for reading trouble history informationfrom the memory built in the vehicle control computer.

[0021] 3. The auxiliary storage means is provided with means fordeciding whether the control processing information in the unerasableregion of the occasionally-erasable nonvolatile memory is updated.

[0022] 4. The vehicle control computer is provided with anothernonvolatile memory for storing the control processing information in theunerasable region in addition to the occasionally-erasable nonvolatilememory.

[0023] 5. Storage connection means for setting the occasionally-erasablenonvolatile memory to the erasable mode when the auxiliary storage isconnected is used.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a block diagram of the electric-power-steeringcontroller of an embodiment of the present invention;

[0025]FIG. 2 is a flow chart showing a procedure for updating thecontrol software in the electric-power-steering controller of anembodiment of the present invention; and

[0026]FIG. 3 is a block diagram of a conventionalelectric-power-steering controller.

BEST MODE FOR CARRYING OUT THE INVENTION

[0027] Operations of an electric-power-steering controller of thepresent invention are described below mainly on the control-softwareupdating operation by referring to the accompanying drawings. FIG. 1 isa block diagram of the electric-power-steering controller of thisembodiment. FIG. 2 is a flow chart showing a procedure for updating thecontrol software of this embodiment. In FIGS. 1 and 2, a symbol same asthat in FIG. 3 shows a portion same as or corresponding to that in FIG.3. In FIG. 1, symbol 52 denotes an input control section for inputting asensor signal to a microcomputer from a torque sensor 50 or speed sensor51, and 59 denotes a storage built in a microcomputer 55. The storage 59comprises an occasionally-erasable nonvolatile memory (e.g. flashmemory) capable of occasionally updating control software from anexternal unit. Symbol 60 denotes a storage connection circuit serving asan input/output interface disposed outside of the microcomputer 55 inthe controller and 70 denotes an auxiliary storage for accessing thestorage 59 through the storage connection circuit 60 to read or updatecontrol software. Then, operations of this embodiment are described inaccordance with the flow chart in FIG. 2. To update control software,the auxiliary storage 70 is first connected to the controller. Thestorage 59 built in the microcomputer 55 is set to the erasable mode bythe storage connection circuit 60 (step S2) when the auxiliary storage70 is connected (step S1). The auxiliary storage 70 successivelydesignates a block number for updating the control software in thestorage 59 (step S3), supplies the update data to the microcomputer 55in the controller, and the microcomputer 55 updates the control softwarein the storage 59 (step S4).

[0028] Control software is updated by excluding an intrinsic-datastorage block (region) serving as an unerasable block (region). Whendesignated blocks are updated, it is confirmed whether updating of everyblock to be updated is completed (step S5). Unless updating iscompleted, step S3 is restated. After updating is completed, theauxiliary storage 70 collates the original data in an unerasable blockwith the post data after updating other blocks in order to confirmwhether the data in the unerasable block is kept in the original state(step S6).

[0029] Moreover, the storage 70 confirms whether the data in theunerasable block is kept in the original state (step S7) and when thedata is kept in the original state, it decides that the data in theunerasable block (region) is not updated and completes updating.However, when it is confirmed that the data is not kept in the originalstate in S7, the storage 70 decides that writing is abnormal anddisplays a trouble indication on a not-illustrated display portion (stepS8).

[0030] However, when storing a part of control software includingunerasable data in another nonvolatile memory, it is unnecessary toestablish an unerasable block (region) to update control software.

[0031] Then, an inexpensive method for preparing the auxiliary storage70 is described below which is an object of the present invention. Asdescribed above, the controller incudes a self-diagnostic function toalways self-diagnose whether the system normally operates. If a troubleoccurs in the system, the controller stops the system and stores thetrouble portion and trouble contents in the memory built in themicrocomputer 55.

[0032] Moreover, a not-illustrated troubleshooting unit is prepared atthe dealer side of a vehicle so that a trouble portion and its contentscan be easily decided when the system is broken. By connecting thetroubleshooting unit to the controller, troubleshooting can beperformed. The troubleshooting unit is generally provided with anoperating section and a display section and moreover, provided with afunction for communication with the microcomputer 55 and a storage.

[0033] The auxiliary storage 70 has many functional sections common tothe troubleshooting unit (e.g. operating section, display section, andcommunicative section). Therefore, by replacing a conventionalcontrol-software storing mask ROM built in the microcomputer 55 with aflash memory and adding a function which works when control software ischanged to update the data in the flash memory to the troubleshootingunit, it is possible to use the troubleshooting unit as the auxiliarystorage 70. Moreover, by adding a data-collation software processingfunction to the troubleshooting unit, an advantage is obtained thaterror correction of update data can be relatively easily realized.

[0034] Therefore, by remodeling an existing troubleshooting unit andadding two or three functions to the unit, it is possible toinexpensively constitute an auxiliary storage having a data updatefunction compared to the case of newly constituting an auxiliary storagehaving the data update function.

[0035] As described above, according to this embodiment, an advantage isobtained that the early change of the control software for performanceimprovement in the electric-power-steering controller can be easilyperformed by a relatively inexpensive unit also in a market afterselling a vehicle by making the control software erasable by theauxiliary storage 70.

[0036] By remodeling an existing troubleshooting unit, it is alsopossible to inexpensively constitute an auxiliary storage 70 compared tothe case of newly constituting an auxiliary storage.

[0037] This embodiment is described about a case of applying theembodiment to an electric-power-steering controller. However, it isneedless to say that the same advantage is also obtained by applying theembodiment to another vehicle controller (e.g. vehicle enginecontroller).

[0038] Industrial Applicability

[0039] The present invention provides a vehicle controller making itpossible to early change control software by a relatively inexpensiveunit also in a market after selling a vehicle by using a controlmicrocomputer having a built-in nonvolatile storage (e.g. flash memory)as a storage for storing the control software.

1. A vehicle controller comprising an occasionally-erasable nonvolatilememory built in a vehicle control computer and storing controlprocessing information and auxiliary storage means for setting anunerasable region to said occasionally-erasable nonvolatile memory andupdating the control processing information in an erasable region to newcontrol processing information.
 2. The vehicle controller according toclaim 1 , wherein said auxiliary storage means is constituted by addingan information updating function to an occasionally-erasable nonvolatilememory in a troubleshooting unit for reading trouble history informationfrom a memory built in a vehicle control computer.
 3. The vehiclecontroller according to claim 1 or 2 , wherein said auxiliary storagemeans is provided with means for deciding whether the control processinginformation in the unerasable region of an occasionally-erasablenonvolatile memory is updated.
 4. The vehicle controller according toclaim 1 , wherein a vehicle control computer is provided with anothernonvolatile memory for storing unerasable control processing informationin addition to an occasionally-erasable nonvolatile memory.
 5. Thevehicle controller according to any one of claims 1 to 4 , wherein astorage connection means is included which sets an occasionally-erasablenonvolatile memory to the erasable mode when an auxiliary storage isconnected.